Purpose: The aim of this in vitro study was to examine the adherence of yeasts to newly
polymerized and water-stored denture base polymers using four Candidastrains with
different cell surface hydrophobicities. Materials and Methods: Thirty-two
autopolymerized denture base polymer specimens were stored in distilled water at 37°C
for 7 days and 32 were newly polymerized. Sixteen specimens of each group were
pretreated with unstimulated mixed saliva (saliva group), and 16 were pretreated with
phosphate-buffered saline ([PBS] PBS group) at 37°C for 1 hour. Hydrophobicity of the
newly polymerized and water-stored specimen surfaces was determined by contact angle
measurements. C guilliermondii, C albicans, C glabrata,and C tropicaliswere grown on
tryptic soy agar. They were pretreated either with saliva or PBS and suspended in PBS.
Four parallel test specimens were incubated without agitation in each yeast suspension at
37°C for 1 hour, washed, and allowed to dry in air. Adherent cells were fixed, gram
stained, and counted from 10 high-power light-microscopy fields of each specimen.
Results: Enhanced adherence of yeasts was observed in water-stored test specimens in
comparison to newly polymerized test specimens. Salivary pellicle reduced the
hydrophobicity of test specimens and the adherence of yeasts. No differences in contact
angles of distilled water between newly polymerized and water-stored polymers were
observed. Conclusion: Yeasts seem to adhere less to newly polymerized than waterstored
denture base polymer. This may be due to the release of residual monomer from
the newly polymerized material.